1. Field of the Invention
The present invention relates to a method for manufacturing a vehicle wheel rim, which is simpler and lower cost than a conventional manufacturing method.
2. The Related Art
In the considerations of reducing the weight of a vehicle body and promoting its control and appearance, a vehicle wheel rim is mostly manufactured by using aluminum alloy material now. Although a conventional method can manufacture a superior performance and appearance of aluminum wheel rim, it still has some defects, For example the strength thereof cannot be further increased, the manufacturing processes thereof are too complicate, and the manufacturing cost thereof cannot be reduced. Three conventional methods for manufacturing an aluminum wheel rim and the defects thereof in reference to the accompanying drawings are described as the followings.
FIG. 1 shows a first conventional gravity casting method for manufacturing an aluminum wheel rim. A wheel-rim-shaped mold cavity A1 is pre-designed in a foundry mold A. Then a melting aluminum alloy is poured into the mold cavity A1. After being cooled, the casting is taken out from the mold A and is processed through a heat treatment and machining procedures to form a wheel rim. However using a foundry mold to manufacture a wheel rim, it easily produces sand holes due to the melting aluminum alloy containing airs. When it is mounted to a wheel tire, a leak will occur. In addition, due to micron sand holes, it is hard to manufacture a wheel rim with chromate treatment to meet market requirements. That further results in a drawback of high manufacturing cost of wheel rim with chromate treatment.
FIG. 2 shows a second conventional welding and spinning method for manufacturing an aluminum wheel rim. Firstly, a rectangular aluminum alloy plate B is rolled up by a rolling machine to form a cylindrical shell B1, then joint the two ends thereof together by a welding process, and finally shape it into a wheel rim B2 by a spinning machine. However this method needs rolling up, welding and spinning procedures so that the manufacturing time and cost thereof are relatively higher. Furthermore, the strength thereof is weaker than that of a wheel rim manufactured by the present invention.
FIG. 3 shows a third conventional spinning method for manufacturing an aluminum wheel rim, which first manufactures two wheel rim parts and then mounts them together using fixing devices. Firstly, two different sizes of aluminum alloy plates C are respectively spun into a first wheel rim pan C1 and a second wheel rim, part C2. The first wheel rim part C1 and the second wheel rim part C2 are then jointed together through a wheel disc, bolts and nuts. However the third method needs two times of spinning, drilling and jointing procedures. Therefore the manufacturing time thereof cannot be further reduced. The condition of being leaky or even loose of the wheel rim may occur due to vibration in the movement of vehicles. And the strength thereof is weaker than that of a wheel rim manufactured by the present invention.
In view of the defects of the above conventional methods for manufacturing an aluminum wheel rim, the present invention provides with a more superior method to manufacture a higher strength, better performance and lower cost of wheel rim.